Hi guys, I have a question. Do the entities of physics really exist in the real world? I've never seen an atom, or an electron, or a photon, or a neutron or a proton. I've never seen these particles with my own eyes. Some of the entities of physics I know for sure exist in the real world like radiation and heat. You can feel the heat of the sun's radiation on your skin in a hot summer day. It's hot. But as for the other entities like electrons, neutrons, photons and quarks I have strong doubts if they really exist in the real world and not just on paper. My question is this: If electrons, protons and neutrons really exist in the real world (and not just in theory or on paper), then why aren't they visible to the naked human eye? Why do we need powerful instruments like scanning tunneling microscopes and particle accelerators to observe these particles for real?